One problem you can have is if the vents see too much turbulence. Bowl pressure that comes from the vents is what pushes fuel into the engine, mess the pressures up and fuel delivery becomes erratic. Make a couple tubes similar to the picture below, if you find that the engine gets rich with them on leave them on and jet the engine for peak MPH. If it makes no change you likely don't need them and don't have an issue at the vents.
